There are a great number of document stacking machines in the prior art, and most of them have been in satisfactory service for many years. As is usually the case, new applications in which the stacking of documents is involved bring out the inadequacies of prior art machinery that were unknown before or were not of major consequence at the time. Stacking apparatus for thermoelectrophotographic printing machinery is subject to a great many requirements heretofor ignored and therefore, among other things, demands relatively precise control and positioning of the effective top of the stack of the documents as they are stacked. An appreciation of the factors involved will be had on inspection of U.S. Pat. No. 3,807,724 to William R. Bartz. The apparatus according to the invention is, therefore, arranged according to a novel method document stack-top height control.
The objects of the invention indirectly referred to hereinbefore and those that will appear as the specification progresses, obtain in a novel combination of mechanical and electric circuit components, constructed individually in accordance with well known principles, and assembled in novel manner in accordance with the invention.